a chemical reaction that can occur in both forward and reverse direction

chemical equilibrium

in a reversible chemical reaction, the point at which the rate of the forward reaction equals the rate of the reverse reaction.

law of chemical equilibrium

states that at a given temperature, a chemical system may reach a state in which a particular ratio of reactant and product concentrations has a constant value

equilibrium constant

the ratio of product concentrations to the reactant concentrations at equilibrium, with each concentration raised to the power equal to the number of moles of that substance in a balanced chemical equation; Keq.

equilibrium constant expression

Keq= [products]/[reactants]

homogeneous equilibrium

all reacting species are in the same phase

heterogeneous equilibrium

equilibrium involving reactants and/or products in more than one phase

le chateliers principle

States that if a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress.

stress

any kind of change in a system at equilibrium, the system shifts in the direction that relieves the stress

boyles law

The relationship between the pressure and volume of a gas at constant temperture; when volume increase, pressure decreases.

catalyst

speeds up the reaction

shifts to right

adda reactant, remove a product lower the tempreature in an exothermic reaction, raise the temperature in an endothermic reaction

shifts to the left

remove a rectant remove a product raise the temperature in an endothermic reaction, lower the temperature in an exothermic reaction

arrhenius model

An acid is a substance that contains hydrogen and ionizes to produce hydrogen ions in aqueous solution; A base is a substance that contains a hydroxide group and dissociates to produce a hydroxide ion in aqueous solution

bronsted lowry

Acids are proton donors - give off H+, bases are proton acceptors - take in H+

conjucate acid

species produced when a base accepts a hydrogen ion

conjugate base

the species produced when an acid donates a hydrogen ion to a base

strong acid

acids that ionize completely

weak acid

acids that ionize partially

strong base

base that dissociates entirely into metal and hydroxide ions

weak base

base that ionizes only partially in dilute solution

Ph

-log[h+]

pOH

-log[oh-]

acidic solutions

pH below 7, pOH above 7

basic solutions

pH above 7, pOH below 7

neutralization reaction

a chemical reaction in which an acid and a base interact with the formation of a salt

titration

a measured amount of a solution of unknown concentration is added to a known volume of a second solution until the reaction between them is just complete

equivalence point

The point during a titration when the number of H+ ions and OH- ions are equal. This is at the middle of the steepest part of the titration curve.

end point

the point in a titration at which a marked color change takes place

redox reaction

A chemical reaction involving the transfer of one or more electrons from one reactant to another; also called oxidation-reduction reaction.

oxidation

The loss of electrons from a substance involved in a redox reaction.

reduction

the gain of electrons by atoms of a substance

reducing agent

a substance capable of bringing about the reduction of another substance as it itself is oxidized

oxidizing agent

the substance that oxifizes another substance by accepting its electrons

oxidation number

positive or negative number that indicates how many electrons an atom has gained, lost, or shared to become stable

electrochemical cell

an apparatus that uses a redox reaction to produce electrical energy or uses electrical energy to cause a chemical reaction

electrodes

an electrically conductive material, usually a metallic strip that conducts electrons into and out of the solution in a half cell

anode

the electrode where oxidation takes place

cathode

the electrode where reduction takes place

cell potential

the difference between the reduction potentials of two half-cells

reduction potential

a measure of the tendency of a given half-reaction to occur as a reduction in an electrochemical cell

salt bridge

A tube that allows the slow transfer of ions and maintains the neutrality of the electrolyte solutions.

electrolytic cell

a cell in which the flow of electrical energy from an external source causes a redox reaction to occur